Bismuth(III) salts mediated regioselective ring opening of epoxides:: an easy route to halohydrins and β-hydroxy nitrates

The ring opening of various epoxides was achieved under mild conditions using bismuth(III) salts. Halohydrins and beta-hydroxy nitrates were efficiently obtained from the corresponding 5 alpha,6 alpha-, 2 alpha,3 alpha-, and 5 beta,6 beta-epoxysteroid using BiCl3, BiBr3 or Bi(NO3)(3) center dot 5H2O. Considerations about the probable reaction mechanism are provided. 2D homo- and heteronuclear correlation NMR spectroscopic techniques were used to unequivocally demonstrate the trans-diaxial nature of the epoxide ring opening. (c) 2007 Elsevier Ltd. All rights reserved.